MR肺通气联合灌注成像的动物模型研究

目的 探讨氧增强MR肺通气成像联合肺灌注成像诊断气道阻塞和肺栓塞(PE)病变的可行性和价值。方法 对8只犬通过肺段动脉水平注入凝胶海绵颗粒复制周围型PE模型，其中5只经自制球囊导管插入二级气道又建立气道阻塞模型。通过吸纯氧前后的图像减影可获得氧增强MR肺通气图像。利用对比剂首次通过法可进行MR肺灌注成像。观察MR肺通气和灌注成像的表现，并与大体病理解剖、核素肺通气-灌注成像和肺血管造影进行对照。结果 MR肺通气和灌注成像在气道阻塞区的表现相匹配，但在肺栓塞区不匹配。气道阻塞区在MR肺通气成像中的缺损区域小于核素肺通气成像。根据信号强度随时间变化曲线，肺灌注异常区可分为灌注缺损和减低区。MR肺通气联合灌注成像诊断肺栓塞的敏感度和特异度分别为75．0％和98．1％；其诊断结果与核素肺通气一灌注成像和肺血管造影的一致性较好(K=0．743、0．899)。结论 氧增强MR肺通气成像联合肺灌注成像可用来诊断肺内气道和血管异常，该方法与核素肺通气-灌注成像类似，并能提供量化的功能信息和更高的时间、空间分辨率，具有临床应用价值。     

肺动脉栓塞诊断的比较影像学

目的评价X线胸片、超声心动图、核素肺灌注扫描、电子束CT（EBCT）、MR肺动脉造影（MRPA）、肺动脉造影（PAG）在肺动脉栓塞（VIE）诊断中的应用价值。方法自2003年7月至2004年3月间临床确诊的PTE患者25例。常规行胸部正侧位摄片、超声心动图、EBCT肺动脉造影、核素肺灌注扫描、MRPA及PAG。PAG由2名有经验医师共同分析每一支肺动脉及其叶段分支，诊断意见作为标准并与其他方法进行对照。结果PAG技术成功率100％，775个受检肺动脉分支中共检出556个分支受累（71．7％）。25例患者中X线胸片提示诊断12例。超声心动图诊断9例，右房室增大21例，肺动脉高压18例。核素肺灌注显像结果显示500个肺段中有247个肺段受累（52．0％），与PAG对照对段的敏感度为64．66％。EBCT肺动脉造影（EBCTPA）的分析显示775个肺肺动脉分支中共有523个主干及叶段分支受累，段以上分支敏感度为94．06％；10例行MRPA的患者中8例检查成功，248各肺动脉分类中共155个分支受累（62．5％），段以上敏感度为81．29％。结论EBCT对PTE的诊断具有较高的敏感度，X线胸片和超声心动图为必不可少的检查手段，EBCT可作为一线影像学诊断方法，核素肺灌注扫描及MRPA可作为二线诊断方法。     

三维并行采集动态增强MRI在肺实质局部灌注中的应用研究

目的评价3D并行采集动态对比增强MRI(dynamic contrast-enhanced MRI,DCE-MRI)技术对肺实质局部灌注成像的可行性。资料与方法采用GE 1.5 T MRI系统,对10名健康志愿者及47例肺部疾病患者行灌注成像;评价肺灌注图像的均匀度,若存在灌注异常区域则计算其与正常肺组织的信号强度之比(RSI)。结果DCE-MRI可以清楚地显示肺实质灌注情况:10名健康志愿者的灌注图像较均匀,未见灌注缺损区。10例肺动脉栓塞(pulmonary embolism,PE)共出现12个楔形灌注缺损区,其中1例双侧PE出现3个灌注缺损区;12例侵犯邻近肺动脉的肺癌,在相应供血区均出现灌注缺损;RSI经单样本t检验差异具有明显的统计学意义(t=-24.74,P<0.05);另25例(20例未侵犯邻近肺动脉的肺癌和5例炎性病变)在对比剂首过肺实质强化达峰值时,病灶局部均呈低信号改变。结论 3D并行采集DCE-MRI技术可在单次屏气状态下完成动态多期扫描,获得全肺的容积灌注成像数据,对MR肺灌注图像采用半量化分析可明显区分出灌注异常区与灌注正常区。     

Feasibility of 3D Partially Parallel Acquisition DCE MRI in Pulmonary Parenchyma Perfusion

目的 评价3D并行采集动态对比增强MRI(dynamic contrast-enhanced MRI,DCE-MRI)技术对肺实质局部灌注成像的可行性.资料与方法 采用GE 1.5 T MRI系统,对10名健康志愿者及47例肺部疾病患者行灌注成像；评价肺灌注图像的均匀度,若存在灌注异常区域则计算其与正常肺组织的信号强度之比( RSI).结果 DCE-MRI可以清楚地显示肺实质灌注情况:10名健康志愿者的灌注图像较均匀,未见灌注缺损区.10例肺动脉栓塞( pulmonary embolism,PE)共出现12个楔形灌注缺损区,其中1例双侧PE出现3个灌注缺损区；12例侵犯邻近肺动脉的肺癌,在相应供血区均出现灌注缺损；RSI经单样本t检验差异具有明显的统计学意义(t＝-24.74,P＜0.05)；另25例(20例未侵犯邻近肺动脉的肺癌和5例炎性病变)在对比剂首过肺实质强化达峰值时,病灶局部均呈低信号改变.结论 3D并行采集DCE-MRI技术可在单次屏气状态下完成动态多期扫描,获得全肺的容积灌注成像数据,对MR肺灌注图像采用半量化分析可明显区分出灌注异常区与灌注正常区.     

磁共振成像对肺动脉栓塞血流动力学的评价

目的:探讨增强磁共振肺灌注成像对肺动脉栓塞血流动力学改变的价值。材料和方法:经放射性核素肺通气-灌注显像和MR肺灌注成像(MRPP)诊断的20例肺动脉栓塞患者和14例健康志愿者,行主肺动脉MR血流编码扫描,通过分析肺实质的信号强度变化率(TROS)、时间-信号曲线、右/左心室内径比及主肺动脉的相关参数(主肺动脉直径、血流峰值、平均流速、单位时间内流量等),比较肺动脉栓塞患者与志愿者间肺动脉血流动力学参数间的差异,评价MR在肺动脉栓塞血流动力学方面的作用。结果:肺栓塞患者组与健康志愿者组肺实质信号强度变化率、峰值时间、主肺动脉直径、右/左心室内径比差异有显著性意义;两组间的主肺动脉峰值流速、平均流速、流量具有统计学差异,肺栓塞患者MR血流编码的肺动脉峰值流速-时间曲线表现为收缩期峰值流时间提前,并可见明显反流。结论:MRI具有诊断肺动脉栓塞的可行性,并可测量肺动脉血流动力学参数变化,粗略估计肺动脉高压程度,有望成为一种研究肺栓塞的无创性影像方法。     

兔实验性急性肺栓塞双源双能量CT与3.0T MR肺动脉成像联合肺灌注成像的对照研究

目的 评价双源双能量CT与3.0TMR诊断家兔急性肺栓塞的准确性.材料与方法 经股静脉注人明胶海绵栓子制作家兔急性肺动脉栓塞模型,栓塞后2h行双能量CT及MRI,得到CT肺动脉图像(CTPA)、双能量肺灌注图像(DEPI)及MR肺动脉图像(MRPA)和MR肺灌注图像(MRPP).以肺叶为单位,记录栓塞的数目和部位.以病理学为金标准,计算上述方法诊断肺栓塞的敏感性、特异性和一致性.结果 CTPA、DEPI检测肺动脉栓塞的敏感性分别为95.8%、95.8%;特异性分别为94.1%、90.2%;MRPA和MRPP的敏感性和特异性分别为83.3%、90.2%;37.5%、98%.CTPA与DEPI对急性肺动脉栓塞检测的吻合度非常好(Kappa值=0.971,P<0.001),DECT(CTPA和DEPI联合)与MRPA对急性肺动脉栓塞检测的吻合度较好(Kappa值=0.796,P<0.001).对于诊断急性肺动脉栓塞DECT与MRPA的差别无统计学意义(P>0.05);但DEPI诊断肺栓塞的准确性(92%)高于MRPP(78.7%),差别有统计学意义(P<0.001).结论 双源CT诊断家兔实验性急性肺动脉栓塞的敏感性略高于MRPA,但差别无统计学意义;DEPI显示肺栓塞所致的灌注缺损优于MRPP.     

3.0T MR动态对比增强肺动脉成像评估肾病综合征患者肺栓塞

目的:以双能量CT肺动脉成像诊断肺栓塞的结果为参考标准,评估3.0TMR动态对比增强肺动脉成像对肾病综合征患者肺栓塞的诊断效能.方法:31例可疑肺栓塞的肾病综合征患者纳入本研究.所有患者在1～3 d内完成双能量CT肺动脉成像和3.0T MR动态对比增强成像扫描.以双能量CT肺动脉和肺灌注融合图像(DECT)诊断结果为参考标准,分别以肺叶和患者为基本研究单位,计算磁共振肺动脉图像(MRPA)、磁共振肺灌注图像(MRPP)及两者融合图像(MRPA/MRPP)诊断肺栓塞的敏感度、特异度、阳性预测值、阴性预测值、准确度.采用Kappa检验分析MRPA/MRPP与DECT图像的诊断一致性.结果:8例患者因磁共振图像质量较差而被排除.23例患者和115个肺叶的影像数据纳入研究.DECT图像共发现14例患者和41个肺叶有肺栓塞.以DECT图像的结果为参考标准,以肺叶为研究单位,MRPA、MRPP、MRPA/MRPP诊断肺栓塞的敏感度、特异度、阳性预测值、阴性预测值、准确度分别为(48.8％、94.6％、83.3％、76.9％、78.3％)、(65.9％、96％、90％、85.5％、85.2％)和(70.7％、94.6％、87.9％、85.4％、86.1％);以患者为研究单位,MRPA、MRPP、MRPA/MRPP诊断肺栓塞的敏感度、特异度、阳性预测值、阴性预测值、准确度分别为(71.4％、66.7％、78.9％、60％、69.6％)、(78.6％、77.8％、84.6％、70％、78.3％)和(92.9％、66.7％、81.3％、85.7％、82.6％).不管是以肺叶还是患者为研究单位,MRPA/MRPP与DECT图像的诊断结果均有较好的一致性,Kappa值分别为0.68、0.62.结论:3.0T MR动态对比增强肺动脉成像能够对肾病综合征患者的肺栓塞进行综合评估,并具有较高的诊断效能.     

3D-CE-MRPA诊断周围性肺栓塞的研究

目的：探讨三维增强磁共振肺血管造影(3D-CE—MRPA)对周围性肺栓塞的诊断价值。方法：8只犬于DSA下经导管将直径2—4mm、长1cm左右的明胶海绵条注入单侧肺动脉后复制为周围性肺栓塞动物模型，然后进行3D-CE—MRPA检查，观察栓塞肺动脉的CEMRPA显示情况及表现形式，分析CEMRPA诊断肺栓塞的敏感性。结果：在DSA显示的26支肺段及其以下水平栓塞肺动脉中，CEMRPA显示了21支，敏感性为80．77％，特异性为100％。栓塞肺动脉主要表现为完全或不完全截断，远侧肺野可见低灌注区存在。多平面重建协助诊断了4支原始图像上显示不清的栓塞肺动脉。结论：3D-CE—MRPA对周围性肺栓塞有较高的诊断敏感性，是诊断周围性肺栓塞的理想方法。多平面重建有助于诊断原始图像上显示不清的栓塞肺动脉。     

低剂量对比剂双能量肺灌注成像评估肺动脉内血栓与灌注缺损间的关系

目的:应用双源CT低剂量对比剂双能量肺灌注成像评估急性肺动脉栓塞患者血管内血栓与肺灌注缺损间的关系,以提高对肺动脉栓塞诊断的准确性。方法:随机选择无肺动脉栓塞患者的低剂量与常规剂量双能量肺灌注成像各15例,对比分析其图像质量;收集20例疑肺动脉栓塞患者行低剂量双能量肺灌注成像;同时获得肺动脉CTA及肺灌注图像。分析肺动脉内有无血栓,以及血栓的部位、数量及形态特征。用双能量肺灌注分析软件判断有无灌注缺损及缺损的部位、形态及范围。对比分析并统计肺动脉内血栓与肺灌注缺损间的关系。结果:肺动脉栓塞患者的低剂量与常规剂量双能量肺灌注成像质量无明显差异(P>0.05)。20例疑似病例中,15例诊断为肺动脉栓塞,其中13例患者肺灌注图像中出现102个肺叶、肺段、或亚段灌注缺损,4例共6个灌注缺损CTA无明确血栓;11例肺动脉CTA显示43个血栓,其中9例血栓与灌注缺损同时存在,2例CTA共5个血栓肺内无灌注缺损。75个灌注缺损与栓塞肺动脉供血范围一致,21个灌注缺损(8段、13亚段)与肺动脉供血范围无关。结论:综合分析双源CT低剂量双能量肺灌注图与CTPA,可以提高肺动脉栓塞诊断的准确性。     

核素肺灌注显像对急性肺栓塞诊断的临床价值

目的评价放射性核素肺灌注显像在诊断急性肺动脉栓塞中的价值。方法对临床怀疑有急性肺动脉栓塞的25例患者进行了放射性核素肺灌注显像,同时行双下肢深静脉显像。结果25例患者中有23例出现不同程度的多发肺段血流灌注异常,其中41个肺段出现放射性缺损区,84个肺段出现放射性稀疏区。25例患者6例双下肢深静脉血栓形成。结论放射性核素肺灌注显像是诊断急性肺动脉栓塞的一种无创伤性的有效的检查方法。     

Virtual pulmonary arterioscopy in pulmonary embolic disease

16 slice multidetector CT provides virtual endoscopic views of the inside of arteries, or any other hollow structures. This is performed non-invasively using post-processing of three-dimensional isotropic image data sets, acquired during standard CT examinations. These virtual endoscopic views are simultaneously correlated with the standard multiplanar reconstructions, with the ability to navigate a virtual camera through the hollow structure under study. Normal and abnormal volume rendered images of the pulmonary arteries are presented in correlation with the multiplanar reformats. The abnormal images show the volume rendered appearances of acute and chronic pulmonary embolic disease. It is also postulated that this technique has a problem solving role in the differential diagnosis of chronic mural emboli from extravascular structures such as adjacent lymph nodes or bronchiolar impaction. This technique may also have a role in medical education, providing clinicians and medical students with interactive three-dimensional representations of disease processes.     

The relationship between pulmonary artery pressure and pulmonary artery diameter in pulmonary hypertension

The pulmonary arteries dilate in response to many factors, principally increased pressure and flow. In patients who have pulmonary arterial hypertension but no increase in flow, we have compared main pulmonary artery size at computed tomography with pulmonary haemodynamic data obtained during right heart catheterisation. In patients with primary pulmonary hypertension and chronic thromboembolic pulmonary hypertension, dilatation correlated with raised pulmonary vascular resistance and reduced cardiac output but not with mean arterial pressure. In patients with chronic lung disease no correlations were shown though a trend between raised pressure and size was observed. We speculate that pulmonary artery compliance is an important factor which determines the degree of dilatation in response to raised pressure. Estimations of pressure cannot be made from measurements of pulmonary artery size without knowledge of the underlying lung disease.     

Computed tomography pulmonary angiogram diagnosis of pulmonary embolism

Over the last decade, contrast-enhanced spiral CT has been established as a non-invasive alternative to catheter angiography and is now regarded as the first-line imaging investigation for the diagnosis of pulmonary embolism (PE). The reported sensitivities for the diagnosis of PE of spiral CT vary from 45 to 100% and the specificities vary from 78 to 100%. Prospective outcome studies have shown a high negative predictive value for a single-detector spiral CT for PE. Patients' outcomes were not adversely affected in these studies when anticoagulation was withheld after a negative CT pulmonary angiogram. The main limitation of single-detector spiral CT has been its limited ability to detect isolated subsegmental PE. However, multidetector spiral CT allows evaluation of pulmonary vessels down to sixth-order branches and significantly increases the rate of detection of PE in segmental and subsegmental levels. The interobserver correlations for diagnosis of subsegmental PE with multidetector spiral CT exceed the reproducibility of selective pulmonary angiography. If appropriate equipment is available (multidetector CT), then CT pulmonary angiogram is safe to be used as the first-line imaging investigation for the diagnosis of PE.     

Unusual pulmonary angiographic findings in suspected pulmonary embolism

Pulmonary arteriography is most commonly performed to diagnose pulmonary embolism. A variety of clinical entities, however, may mimic pulmonary embolism both clinically and scintigraphically. Five patients with abnormal pulmonary arteriograms resulting from diseases other than pulmonary embolism are presented. The clinical, radiographic, and pathologic findings and long-term follow-up in these patients are described. Awareness of the angiographic patterns seen in these unusual cases is important in the differential diagnosis of pulmonary thromboembolism.     

CT-determined pulmonary artery diameters in predicting pulmonary hypertension

This study was to determine if the diameters of pulmonary arteries measured from computed tomographic (CT) scans could be used 1) as indicators of pulmonary artery hypertension and 2) as a reliable base for calculating mean pulmonary artery pressure. The diameters of the main, left, proximal right, distal right, interlobar, and left descending pulmonary arteries were measured from CT scans in 32 patients with cardiopulmonary disease and in 26 age- and sex-matched control subjects. Diameters were measured using a special computer program that could display a CT density profile of the artery and its adjacent tissues. The upper limit of normal diameter for the main pulmonary artery was found to be 28.6 mm (mean + 2 SD). In the patient group, the diameters were correlated with data from cardiac catheterization. In these patients, a diameter of the main pulmonary artery above 28.6 mm readily predicted the presence of pulmonary hypertension. The calculated cross-sectional areas of the main and interlobar pulmonary arteries (normalized for body surface area [BAS]) were found to give the best estimates of mean pulmonary artery pressure (r = 0.89, P less than 0.001 and r = 0.66, P less than 0.001). Multiple regression analysis gave the useful equation: mean pulmonary artery pressure = -10.92 + 0.07646 X area of main pulmonary artery/BSA + 0.08084 X area of the right interlobar pulmonary artery/BSA (r = 0.93, P less than 0.0001). Because CT allows precise, noninvasive measurement of the diameter of pulmonary arteries, it can be of value in detecting pulmonary hypertension and estimating mean pulmonary artery pressure.